Genetic resources for future crop evolution
As in any group of plants or animals in nature, the future evolution of crop plants depends upon the availability of genetic diversity. The course of future crop evolution depends upon new demands that may emerge from existing crops and constraints which may develop. It has been indicated in the previous chapters that the genetic diversity of crop plants has accumulated mainly by human selection, either consciously or unconsciously. In many instances the selected characters were of low adaptive value in natural habitats and could survive only under human care. Traditionally, crop plants were maintained as mixtures of genotypes which could respond to ecological fluctuations in their natural environment. Modern cultivars, on the other hand are much more uniform morphologically, physiologically and genetically. Both the existing land races and bred cultivars are the natural stock for future evolution of our crops. Crop plants also share a great deal of their genetic property with their wild progenitors, but because of the founder effect and barriers to hybridization only part of the genetic diversity of the wild progenitors is present in their domesticated derivatives. Another source of diversity is the more distantly related species of the secondary gene pool of the crops. Their exploitation is more laborious and time consuming but they may possess diversity which is absent in the primary gene pool.
KeywordsGenetic Resource Crop Plant Target Species Germplasm Collection Wild Relative
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